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University of Minnesota Extension

Flowering rush

Quick facts

Flowering rush is a prohibited invasive species. It is illegal to possess, import, purchase, transport, or introduce these species (including hybrids or cultivars) except under a permit or statutory exemption. Transport directly to the Minnesota Department of Natural Resources in a sealed container for identification or reporting purposes is permitted.

  • Flowering rush can produce dense monotypic stands.
  • May displace native species and interfere with boat traffic.
  • Flowering rush should be reported. 

See the Minnesota Department of Natural Resources recommendations for reporting invasive species.

How to identify flowering rush

  • Flowering rush (Butomus umbellatus) is a perennial aquatic herbaceous plant that grows up to six feet tall along shores in shallow water.
  • Can grow submerged in waters up to ten feet without producing flowers.
  • When not in flower, it looks like common native shoreland plants and may be difficult to identify.


  • Triangular in cross-section, may be more rounded toward the base.


  • Sword shaped, triangular in cross section, often twist near top.


  • Pink flowers are arranged in umbrella shaped clusters (umbels).
  • Blooms late June to August.


  • Populations in the eastern U.S. produce seeds.
  • Only one Minnesota population (Forest Lake) is known to produce viable seeds.


  • Reproduces by vegetative spread from its rootstock in the form of bulbils.
  • Both seeds and bulbils are dispersed by water current.
Flowering rush
Flowering rush bulbils


Angela Gupta, Extension educator; Amy Rager, Extension educator; Megan M. Weber, Extension educator

Reviewed in 2019

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